WO1991013105A1

WO1991013105A1 - Methacrylic resin molding material for optical information recording medium

Info

Publication number: WO1991013105A1
Application number: PCT/JP1991/000225
Authority: WO
Inventors: Suehiro Tayama; Yasunori Kawachi; Shigeaki Sasaki
Original assignee: Mitsubishi Rayon Co., Ltd.
Priority date: 1990-02-23
Filing date: 1991-02-22
Publication date: 1991-09-05
Also published as: EP0470260A4; KR920702857A; EP0470260A1

Abstract

A methacrylic resin molding material comprising a copolymer composed of 80 to 99.5 wt. % of methyl methacrylate units and 20 to 0.5 wt % of the units of at least one acrylate monomer selected from the group consisting of 2,2,2-trifluoroethyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, isobornyl acrylate and tricyclo[5.2.1.0?2,6]decanyl acrylate. It can be used advantageously as an excellent molding material for producing an optical information recording medium, because it has excellent heat resistance and good fluidity while retaining excellent optical and mechanical characteristics inherent in methacrylic resins, so that it can enhance the productivity in molding.

Description

Description Metallic resin molding materials for optical information recording media

The present invention relates to a methacrylic resin molding material for an optical information recording medium such as a video disk. Background art

Methacrylic resin is used for various optical devices because it has good moldability, and the molded product has excellent transparency and useful optical properties. Recently, it has been used as a substrate for optical information recording media such as video discs, taking advantage of its excellent properties.

Optical information recording medium substrates require resin materials that have low optical strain, satisfy mechanical strength in practical use, and have excellent heat resistance and moldability. Due to the growing demand for discs, there is a strong demand in the market to improve the productivity of discs in injection molding, that is, to shorten the molding cycle. Therefore, the performance required of the resin material must be good fluidity and high heat resistance. As long as the material has the same fluidity, a material having higher heat resistance can be removed from the mold even at a higher temperature, thereby shortening the molding cycle.

Methacryl resin for optical information recording media is A copolymer of acrylate and ethyl acrylate has been proposed (JP-A-57-123208). However, when using methyl methacrylate and ethyl acrylate, if the fluidity is improved, the optical distortion is reduced, but the heat resistance is reduced and the mechanical strength is reduced. Because of the surface, it was difficult to improve productivity during molding. That is, if the copolymerization ratio of ethyl acrylate is increased in order to improve the fluidity, the heat resistance is greatly reduced, which is not preferable for practical use. Also, if the method of decreasing the molecular weight is used while maintaining the copolymerization ratio of ethyl acrylate in order to increase the fluidity while maintaining the heat resistance, the mechanical strength becomes practically unsatisfactory. .

At present, substrates for optical information recording media, especially video discs and discs, are mainly manufactured by injection molding, and the molding cycle is made in consideration of productivity, and the heat resistance of resin and Determined by liquidity. In order to improve productivity in injection molding, the optical distortion is small, transparency and mechanical strength are not impaired, but the resin fluidity is improved, and the cooling time during injection molding is reduced. It is necessary to improve the heat resistance for the purpose of the above. However, known molding materials have a problem that when the heat resistance is improved, the flowability and the mechanical strength are lowered. Disclosure of the invention

In view of this situation, the present inventors have conducted various studies focusing on methacrylic resin as a molding material for an optical information recording medium. However, they have found that a substrate for an optical information recording medium without the above-mentioned problems can be manufactured with high productivity, and arrived at the present invention.

That is, the present invention relates to a method of preparing a methyl methacrylate unit of 80 to 99.5% by weight and 2,2,2-trifluoroethyl acrylate, a silicone acrylate, Enirua click Li rate, small selected from Benjirua click Li rate, Lee Seo Borunirua click Li rate and Application Benefits consequent π [5, 2, 1, 0 Ζ · 6 ] the group consisting of deca Nirua click re, single DOO It is intended to provide a resin molding material for optical information recording media, comprising a copolymer comprising at least one kind of acrylate monomer unit in an amount of 20 to 0.5% by weight. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph showing the relationship between the heat deformation temperature and the melt flow rate, which shows the excellent heat resistance and fluidity of the methacrylic resin molding material according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION When the copolymerization ratio of the copolymer constituting the methacrylic resin molding material of the present invention is out of the above range, while maintaining the mechanical strength of the molded article, It is not possible to improve heat resistance to increase productivity during mass production. That is, if the methyl methacrylate unit exceeds 99.5% by weight, the molecular weight must be reduced in order to maintain the molding fluidity of the resin, and as a result, the mechanical strength decreases. On the other hand, if the acrylic rate unit exceeds 20% by weight, The mechanical strength is remarkably inferior or the heat resistance is inferior, which is not preferable.

The melt flow rate of the copolymer is 0.5 to 50 g / 10 minutes, especially 5 to 50 g, measured at a load of 3.8 kg based on ASTM-Dl'238. / 10 minutes is preferred. If the melt flow rate is less than 0.5 g / 10 minutes, the transferability of information from the mold is inferior, and the optical distortion of the molded product tends to increase. On the other hand, if it is greater than 50 g / 10 minutes, the mechanical strength tends to decrease. Consider the use of information recording media! ; If, machine栻的is a strength, 3 0 0 kg / cm ² or more on the basis of tensile strength A STM D 638, and particularly preferably between 4 0 0 kg / cm ² or more.

The thermal deformation temperature of the copolymer is preferably a value measured at a load of 8.56 based on ASTM D648, preferably 70 ° C or more, to prevent thermal deformation during molding and use. More preferably, the number is 80 or more. If the heat distortion temperature is lower than 70, the heat resistance of the molded body is inferior, and particularly, the heat deformation during molding and during use may increase, which is not preferable.

By using a methacrylic resin molding material that satisfies the above-mentioned conditions, productivity during molding can be improved compared to before, and excellent optical transparency and mechanical strength with small optical distortion can be achieved. A molded article having a degree can be obtained. Also, it is clear from the attached FIG. 1 that the resin composition of the present invention has excellent balance between fluidity and heat resistance.

In producing the molding material of the present invention, a conventional method for producing an acrylic resin such as suspension polymerization, bulk polymerization or solution polymerization is used. Can be. If necessary, a stabilizer, a release agent, a lubricant, a plasticizer, a dye, and the like can be added to the acrylic resin molding material of the present invention.

The molding material of the present invention thus obtained can be applied to both injection molding and compression molding.

The methacrylic resin molding material of the present invention has excellent heat resistance and good fluidity while maintaining the excellent optical and mechanical properties inherent to methacrylic resin. As an excellent molding material that can also improve its properties, it can be advantageously used in the production of optical information recording media.

Hereinafter, the present invention will be further described with reference to examples. The measurement of each characteristic value in the examples was performed by the following method.

(1) Heat deformation temperature (HDT)

Measured under a load of 18.56 kg according to ASTM D648.

(2) Molelet flow rate (MFR)

It was measured with a load of 3.8 kg according to ASTM-D1238.

(3) Tensile strength and tensile elongation

A dumbbell A-type test piece was injection-molded with Nissei Resin Co., Ltd., PS-60E, and measured according to ASTM-D638.

(4) Light transmittance

A 300 mm dia. Disk (1.2 mm t) was injection-molded using a Meiki Seisakusho M-200 dynamometer by cylinder injection (cylinder temperature 260 ° (:), Ί cm from center. Was measured in the range of 500 to 900 nm using Shimadzu UV-160A. (5) birefringence (retardation)

Birefringence of point 7 cm from the center of the same disk molded article as described above (Retardation) a polarizing microscope (Nikon, ΟΡΠΡΗΟΤ-POL, SENARMONT COMPENSATOR, used wavelength 546nm _s single pass) was measured with a.

In addition,% and part in the examples indicate% by weight and part by weight, respectively.

Examples 1 to 18

In 100 parts of the monomer mixture in the proportions shown in Table 1, 0.35 parts of n-octylmercaptane were dissolved, 0.44 parts of lauroyl baroxide as a polymerization catalyst, and stearyl alcohol as a release agent. 0.1 part, copolymer of methyl methacrylate and 3-methacryloyl oxypropane sulfonic acid resin as a mesogenic polymerization dispersant 0.01 part, sodium sulfate 0.15 parts of lithium and 145 parts of water as a dispersion medium were introduced into a glass flask polymerization apparatus equipped with a stirrer and a thermometer, and the mixture was polymerized at 80 ° C. After reaching, the mixture was kept at 95'C for 30 minutes, cooled, filtered, washed with water and dried to obtain a beaded polymer. The obtained polymer was kneaded with a 40 mm extruder manufactured by Tanabe Plastics Machinery Co., Ltd. with 240, and pelletized.

Various evaluations were performed using the obtained pellets, and the results shown in Table 1 were obtained. In each of the examples, the light transmittance was 91% or more in the wavelength range of 500 to 900 nm, and the birefringence (retardation) was as good as 20 nm or less. And. Comparative Examples 1 to 9

The same operation as in Example 1 was carried out except that 100 parts of the monomer mixture in the proportions shown in Table 2 were used, and the results shown in Table 2 were obtained. The polymer obtained by copolymerizing 30 parts of 2,2,2-trifluoroethyl acrylate and 70 parts of methyl methacrylate (Comparative Example 1), and cyclohexane The polymer obtained by copolymerizing 30 parts of hexyl acrylate and 70 parts of methyl methacrylate (Comparative Example 2) has extremely low heat resistance, so that it can be used for extrusion molding. Cannot be pelletized and lacks practicality. Further, a polymer obtained by copolymerizing 30 parts of phenylacrylate and 70 parts of methylacrylate (Comparative Example 3), 30 parts of benzylacrylate, and A polymer obtained by copolymerizing 70 parts of methyl methacrylate (Comparative Example 4), 30 parts of isobutyl acrylate and 70 parts of methyl methacrylate A polymer obtained by copolymerization (Comparative Example 5), and tricyclo

(5,2, 1.0 ² · ⁶ J Dekanirua click Li rate 2 0 parts of main Chirume Tak Li rate 8 0 parts of a copolymerized to the polymer (Comparative Example 6), the mechanical strength is small In addition, the polymer obtained by polymerizing 100 parts of methyl methacrylate (Comparative Example 9) had an MFR of 22.5 g Z 10 minutes, and the polymer of Comparative Example 7 Although the fluidity is almost the same as that of Comparative Example 7, the tensile strength is less than half of that of Comparative Example 7, and is not practical.

From the results of Examples 1 to 18 and Comparative Examples 7 to 8, the relationship between MFR and HDT is as shown in Fig. 1.For example, when MFR is to obtain a molding material of 20 g ZIO, Benjiakuri The copolymer of methacrylate and methyl methacrylate has about 2.5 improvement in HDT compared to the copolymer of methyl methacrylate and ethyl acrylate. Copolymers of 2,2,2-trifluoroethyl acrylate and methyl methacrylate, and copolymers of hexyl acrylate and methyl methacrylate, The HDT shows about 4 improvement over the copolymer of chilmethacrylate and etilacrylate. Also, a copolymer of tricyclo [5,2,1,0 ² • ⁶ ] decanyl acrylate and methyl methacrylate, isobornyl acrylate and methyl methacrylate The copolymer of phenylacrylate and methyl methacrylate has about 7 • C improvement in HDT compared to the copolymer of methyl methacrylate and ethyl methacrylate. Is recognized. As a result, the copolymer of methyl methacrylate and the acrylate shown in Table 1 is more effective than the copolymer of methyl methacrylate and ethyl acrylate. It can be said that its formability is good in terms of productivity. Industrial applicability

The methacrylic resin molding material of the present invention can be advantageously used for producing an optical information recording medium. Table 1

First 1

Table 2 Comparison W1 Comparison W2 Comparison Comparison Example 4 Comparison 5 Comparison Comparison Example 7 Comparison Example 8 Comparison Methylmethacrylate 70 70 70 70 70 80 90 85 100

2, 2, 2 Trifluoride α 30

Etylac Relate

Simple Shio ο 丰 sil 30

Quantify rate

Rest

{± phenylacrylate 30

Including

Pair

Benzyl benzylate-[%]

I Soporuniruaku re-rate one - eleven 30 one -. Door Li Sik Russia 2.1, 0 ', ^4] 20

Decanilac Relate

Etylac Rerate 10 15

η Octyl mercaptan 0.35 0.62

[Part 1

Lau Roy Rupaxide 0.44

120.0 140.5 132.0 .38.2 22.5 42.3 22.5-

HDTCC1 75.6 64.3 73.2 88.8 81.9 73.8 103.1 Tensile strength ikg / oil 250 290 240 290 640 550 210 210 Tensile elongation [% 1 0.8 1.0 0.9 2.0. 3.4 2.5 0.7

Claims

The scope of the claims

1. Methyl methacrylate unit: 80 to 99.5% by weight, 2,2,2-trifluoroethyl acrylate, cyclohexyl acrylate, and funicular acrylate At least one selected from the group consisting of rate, benzyl acrylate, isovol acrylate, and tricyclo [5, 2, 1, 0 ² · ⁶ ] power acrylate. A methacrylic resin molding material for an optical information recording medium, comprising a copolymer comprising 20 to 0.5% by weight of one type of acrylic monomer unit.

2. The molding material according to claim 1, wherein the melt flow rate of the copolymer is 0.5 to 50 g / 10 minutes as measured at a load of 3.8 kg according to ASTM-D1238.

3. The molding material according to claim 2, wherein the melt flow rate is 5 to 50 g / 10 minutes.

4. The molding material according to claim 1, wherein the heat distortion temperature of the copolymer is 70 or more directly measured at a load of 18.5 kg based on ASTM-D648.

5. The molding material according to claim 4, wherein the heat distortion temperature is 80'C or higher.

6. Both the tensile strength of the polymer is ASTM- D638 in basis 3 0 0 kg / cm ² or more, the molding material of claim 1, wherein.

7. The molding material according to claim 6, having a tensile strength of 400 kg / cm ² or more.